Process for manufacturing a thin film slider with protruding R/W element formed by chemical-mechanical polishing

ABSTRACT

A composite thin film slider with a protruding R/W device formed by chemical-mechanical polishing to protrude above its substrate and thereby reduce the distance between the R/W device and the recording media. The slider includes a ceramic or non-ceramic substrate with a substantially planar bearing surface, and a R/W device. The R/W device includes an insulator and certain conductive R/W components, deposited onto the substrate&#39;s deposit end. The R/W components may include, for example, a magnetic shield layer, a MR stripe layer, and a magnetic pole tip layer, all layered over the deposit end of the substrate. The R/W components protrude from the insulator sufficiently to extend past the substrate&#39;s bearing surface. To manufacture this slider, a substrate with the R/W device deposited thereon is polished with a lapping slurry to disproportionately erode the substrate and insulator with respect to the R/W components. The R/W components therefore protrude from the insulator and the ceramic substrate&#39;s bearing surface.

This application is a division of application Ser. No. 08/481,574, filedJun. 7, 1995, U.S. Pat. No. 5,617,273.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to thin film sliders for use with magneticdata storage media such as disk and tape media. More particularly, theinvention concerns a composite thin film slider with a protrudingread/write ("R/W") device formed by chemical-mechanical polishing toprotrude above its substrate and thereby reduce the magnetic spacingbetween the R/W device and the recording media.

2. Description of the Related Art

One of the most important parts of a tape or disk drive is its recordinghead, also called a "slider." The slider is one factor in determiningthe efficiency, density, speed, and accuracy with which data can be readfrom and written to magnetic recording media. As engineers areincreasing the performance requirements of their recording systems, theyare concurrently researching improved designs for sliders. One of thechief goals in designing a slider is minimizing the distance between therecording medium and the region of the slider that actually performsread and write operations, i.e. the R/W "device." This distance may bereferred to as the "magnetic spacing." With a smaller magnetic spacing,the R/W device can store data more compactly on the recording medium,thereby increasing the recording medium's storage capacity.

One of the chief obstacles to reducing magnetic spacing is thedifference in elevation between the slider's substrate and its R/Wdevice. As discussed below, known techniques for lapping and polishingtypically produce sliders with R/W devices that are eroded below thelevel of the adjacent substrate. This increases the magnetic spacing.

Sliders are typically derived from a wafer 100 (FIG. 1) composed of asubstrate of "N58" (a titanium carbide (TiC) and aluminum oxide (Al₂ O₃)mix) and an overcoat comprising read/write device metallurgy and aninsulator such as Al₂ O₃. Depending upon the size of the wafer 100 andthe sliders to be cut, the wafer 100 may produce from 500 to 10,000individual sliders. The components of each slider's R/W device aredeposited onto a surface 102 of the wafer's substrate. These componentsinclude, for example, pole tips, magnetoresistive ("MR") elements,shields, and the like. These components are usually made from aluminumoxide, metals, or another material different than the substrate.

The next step in preparing an individual slider is to cut the wafer 100into rows, such as the row 200 (FIG. 2). The row 200 has a "deposit end"102 (corresponding to the surface 102 of FIG. 1) and a bearing surface202. The row 200 may have dimensions of about 47 mm×2 mm×0.5 mm, forexample. Next; the bearing surface 202 is smoothed by conventionallapping and polishing techniques to provide sliders with precisedimensions. After air bearing fabrication, the row 200 is then cut intoindividual sliders, such as the slider 300 (FIG. 3). The slider 300includes a substrate 302 and a comparatively small R/W device, which isnot shown but occupies an area 304 of the deposit end 102. The R/Wdevice 304 is deposited along the deposit end 102 of the substrate 302.Prior to cutting the row 200 into individual sliders, the deposit end102 of the individual slider 300 (FIG. 3) constituted part of thesurface 102 of the row 200 (FIG. 2).

FIG. 4 illustrates the substrate 302 and the R/W device 304 in greaterdetail. The R/W device 304 includes an insulator 408, multiple shields400-401, an MR stripe 402, and a pole tip 404. The slider 300 may alsoinclude a nearly uniform carbon overlayer 406 covering the substrate 302and R/W device 304, to protect the slider 300 from wear, contamination,or damage.

For many applications, the slider 300 of FIGS. 3-4 satisfies its users'expectations. However, for applications requiring a higher recordingdensity, known sliders may not be completely adequate. As shown in FIG.4, known slider manufacturing processes yield a R/W device 304 that isrecessed in elevation with respect to the bearing surface 202 of thesubstrate 302, usually by about 15-20 nm. Additionally, the shields400-401 MR stripe 402, and pole tip 404 are recessed with respect to theinsulator 408. Accordingly, when the slider 300 is implemented in amagnetic recording device, the critical components of the R/W device 304may be excessively distanced from the recording medium (not shown),thereby reducing the slider's recording density.

SUMMARY OF THE INVENTION

The present invention concerns a composite thin film slider with aprotruding R/W device formed by chemical-mechanical polishing toprotrude above its substrate and thereby reduce the distance between theR/W device and the recording media.

The slider of the invention includes a substrate and a R/W device, wherethe R/W device further includes an insulator and various conductive R/Wcomponents. These components may include, for example, multiple shields,an MR stripe, and a pole tip. The slider may also include a nearlyuniform overlayer 606 (such as a carbon-based layer) covering thesubstrate and R/W device to protect the slider from wear, contamination,and damage.

As a result of the process for manufacturing the slider, the substratedefines a smooth, nearly planar bearing surface. However, due to therelative hardnesses of the substrate and the insulator, the surface ofthe insulator and R/W device may be recessed somewhat with respect tothe bearing surface. Unlike known sliders, components of this R/W deviceprotrude from the insulator, and furthermore rise above the extendedplane of the substrate's bearing surface. If desired, the overlayer maybe thinned or removed proximate the R/W device. This permits the R/Wdevice, which still protrudes above the extended plane of thesubstrate's bearing surface, to ultimately reside nearer to therecording medium during operation of the slider.

A different aspect of the invention comprises a method for manufacturinga slider such as that described above, employing chemical-mechanicalpolishing to ensure that the components of the slider's R/W deviceprotrude above the bearing surface of its substrate and thereby reducethe distance between the R/W device and the recording media. Moreparticularly, a substrate is manufactured with a deposit end containingmultiple embedded R/W devices. The material of the substrate maycomprise a ceramic, such as TiC/Al₂ O₃ ("N58"), silicon carbide, orzirconium oxide, or a non-ceramic such as silicon. Each R/W device onthe wafer preferably includes a insulator, preferably formed from aninsulating material such as alumina or a suitable oxide material. EachR/W device additionally includes conductive components such as multipleshields, an MR stripe, and a pole tip.

After creating the wafer and the R/W devices contained thereon, thewafer is cut into rows. Then, a bearing surface of each row is polished.The rows are then polished by mounting the rows to a lapping machine andchemically-mechanically polishing the rows' bearing surface with apolishing slurry. In a first embodiment, the rows may be polished byfloat polishing the rows in a slurry that has a partial chemicalaffinity for the substrate. In the float polishing embodiment, theslurry comprises (1) a solid component such as an oxide-based materialsuch as silicon dioxide, aluminum oxide, cerium oxide, or diamond alongwith (2) a liquid vehicle such as water or glycol. Due to the chemicaland mechanical relationship between the slurry, the substrate, theinsulator and the R/W components, the slurry erodes the insulator andsubstrate disproportionately more than the conductive R/W components. Innon-contact or float polishing, the solid component of the slurry (i.e.,the abrasive) has a diameter less than the thickness of the liquid layerseparating the lapping surface and the surface of the lap plate.

In a second embodiment, the wafer may be polishedchemically-mechanically by contact polishing the wafer in a slurry thathas a chemical-mechanical affinity for the substrate. In the contactpolishing embodiment, the slurry may comprise a similar combination asdescribed above for use in float polishing. In the second embodiment,the slurry erodes the substrate and the insulator disproportionatelymore than the conductive R/W components due to (1) the mechanicalabrasion of the slurry against the wafer, and (2) the chemicalrelationship between the slurry, the substrate, the insulator, and theconductive R/W components.

After contact or float polishing, the substrate and insulator regions ofthe rows preferably define smooth, nearly planar surfaces. Due to therelative harnesses of the substrate and the insulator, however, thesubstrate surface may be recessed somewhat with respect to the insulatorsurface. Unlike known sliders, though, the shields, MR stripe, and poletip preferably protrude from the insulator surface, and furthermore riseabove the extended plane of the substrate's bearing surface.

At this point, the rows' bearing surface may be processed to define anair bearing surface thereon. Also, a nearly uniform overlayer may bedeposited over each substrate and R/W device, to protect the individualsliders from wear, contamination, and damage. If desired, the overlayermay be thinned or removed proximate the components of the R/W device, byfurther contact or float polishing to permit the components, stillprotruding above the extended plane of the bearing surface, to residenearer to the recording medium during operation of the slider. Next, therows are cut into individual sliders.

The invention affords its users with distinct advantages. For instance,the invention provides a thin film head with a R/W device that protrudesabove its substrate, thereby decreasing the magnetic spacing between theslider and the recording medium. This improves the coupling between thetwo, resulting in increased storage density.

BRIEF DESCRIPTION OF THE DRAWINGS

The nature, objects, and advantages of the invention will become moreapparent to those skilled in the art after considering the followingdetailed description in connection with the accompanying drawings, inwhich like reference numerals designate like parts throughout, wherein:

FIG. 1 is a perspective view of a known wafer 100;

FIG. 2 is a perspective view of a known row 200 cut from a wafer 100;

FIG. 3 is a perspective view of a known slider 300;

FIG. 4 is a partial cross-sectional view of the slider 300, taken alongthe line 4--4;

FIG. 5 is a perspective view of a slider 500 in accordance with theinvention;

FIG. 6 is a partial cross-sectional view of the slider 500, taken acrossthe line 6--6, in accordance with the invention; and

FIG. 7 is a flowchart illustrating an exemplary sequence of method stepspursuant to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Slider Composition

Broadly, the present invention concerns a composite thin film head or"slider" with a R/W device that advantageously protrudes above itssubstrate, thereby reducing the distance between the R/W device and therecording media during operation of the slider.

FIG. 5 depicts an example of a slider 500 that embodies the invention.The slider 500 generally comprises a thin rectangular substrate 502 witha relatively small R/W device 504 formed upon a deposit end 506 of thesubstrate 502. The end 506 generally corresponds to the deposit end 102of a conventional slider 300. The substrate 502 may comprise a ceramicmaterial, such as TiC/Al₂ O₃ (called "N58"), silicon carbide, orzirconium oxide, or a non-ceramic material such as silicon. The slider500 includes a bearing surface 508 that generally corresponds to thebearing surface 202 of a conventional slider 300.

FIG. 6 illustrates the R/W device 504 in greater detail. The R/W device504 includes an insulator 600, preferably formed from an insulatingmaterial such as alumina. The insulator 600 is layered on top of thedeposit end 506. The R/W device 504 includes various conductive R/Wcomponents 605, such as multiple shields 601-602, an MR stripe 603, anda pole tip 604. The R/W components 605 are preferably formed from amagnetic material such as an iron-nickel combination, or another knowncomposition. The slider 500 may also include a nearly uniform overlayer606 (such as a carbon-based layer) covering the substrate 502 and R/Wdevice 504, to protect the slider 500 from wear, contamination, anddamage.

As a result of the process for manufacturing the slider 500 (discussedbelow), the bearing surface 508 defines a smooth, nearly planar surface.Likewise, the insulator 600 may define a smooth, nearly planar surface610. Due to the relative hardnesses of the substrate 502 and theinsulator 600, however, the surface 610 may be recessed somewhat withrespect to the bearing surface 508, on the order of 10-15 nm. Unlikeknown sliders, the R/W components 605 preferably protrude from theinsulator's surface 610, and furthermore rise above the extended planeof the bearing surface 508. In one embodiment, the overlayer 606 may bethinned proximate the R/W components 605. This permits the R/Wcomponents 605, still protruding above the extended plane of the bearingsurface 508, to reside still nearer to the recording media duringoperation of the slider 500.

CONSTRUCTION OF SLIDER

In addition to the improved slider described above, the presentinvention contemplates a method for manufacturing such a slider,employing chemical-mechanical polishing to ensure that the R/Wcomponents of the slider protrude above their substrate, therebyreducing the distance between the R/W device and the recording media.More particularly, FIG. 7 shows an exemplary sequence of operationalsteps 700 in accordance with the invention. To illustrate the steps 700more clearly, reference is also made to FIGS. 1-2 and 5-6.

After the routine 700 is initiated in task 702, a ceramic wafer 100 ismanufactured in task 704 with a deposit end 102 containing multipleembedded R/W devices (not shown). Task 704 may be performed, forexample, with conventional techniques for creating the wafer 100 and R/Wdevices. For example, task 704 may involve depositing a multiplicity ofR/W devices onto the deposit end 102 of a 125 mm wafer 100 using knowntechniques.

As discussed above, the material of the wafer 100 comprises a ceramic,such as N58, silicon carbide, or zirconium oxide, or a non-ceramic suchas silicon. Also as discussed above, each R/W device (such as the R/Wdevice 504) is deposited on the end 102 (corresponding to the end 506 inthe case of the slider 500), with the layers shown in FIG. 6. A R/Wdevice 504, for example, preferably includes an insulator 600 andcertain R/W components 605. The insulator 600 is, preferably formed froman insulating material such as alumina, or another oxide. The conductiveR/W components 605 may include multiple shields 601-602, an MR stripe603, and a pole tip 604, for example. To form a R/W device 504, layersof insulator and appropriate conductive material are alternatelydeposited on the end 102, in appropriate thicknesses to generate thelayering shown by the R/W device 504 of FIG. 6.

After creating the wafer in task 704, the wafer is sliced into rows intask 705 and the bearing surface 202 (corresponding to the surface 508in the case of the slider 500) is polished in task 706. Specifically, intask 706, the wafer is mounted to a lapping machine and mechanically orchemically-mechanically polished with a polishing slurry. In a firstembodiment, the wafer may be polished by "float polishing" the wafer ina slurry that has a partial chemical affinity for most, if not all of,the materials in the slider 500. In the float polishing embodiment, theslurry comprises (1) a solid component such as an oxide-based materiallike silicon dioxide, aluminum oxide, cerium oxide or diamond, alongwith (2) a liquid vehicle such as water or glycol. In embodiments wherethe substrate 502 is made from "N58", a preferred slurry comprises asolution of 30-1000Å silicon dioxide particles (2%) immersed indistilled water (98%). A preferred speed of rotation during floatpolishing is 50-68 RPM, with a non-linear rotary pattern. Floatpolishing may be conducted for about 5-60 minutes, for example.

During "float polishing", the surface 508 of the row 200 is separatedfrom the lapping plate by hydrostatic repulsion. Mechanical polishingoccurs only by contact between the surface 508 and particles of thepolishing slurry rather than the lapping plate. Due to the chemical andmechanical relationship between the slurry, the substrate, theinsulator, and the R/W components 605, the slurry erodes the insulator600 and substrate 502 disproportionately more than the conductive R/Wcomponents 605. The components 605 of the R/W device 504 are thereforeelevated above the extended plane of the bearing surface 508 of thesubstrate 502.

In a second embodiment, the wafer may be polishedchemically-mechanically, by contact polishing the wafer in a slurry thathas a chemical and mechanical affinity for the materials in the slider.In the contact polishing embodiment, the slurry may comprise a similarcombination as described above for use in float polishing. Here, apreferred speed of rotation during float polishing is 50-58 RPM, with anon-linear rotary pattern and a lap pressure of approximately 100 g/cm².The lapping plate may comprise, for example, a tin-based material cutwith a grooved float polishing pattern having a roughness of less than 2microns on its flat areas. Alternatively, a standard tin lapping platemay be used. Contact polishing may be conducted for about 5-60 minutes.

During contact polishing, the bearing surface 508 of the row 200contacts the lapping plate, which results in faster rates of abrasion.Abrasion may be accelerated by using a more abrasive lapping plateand/or by slowing the lapping plate's speed of rotation.

In the contact polishing embodiment, the slurry erodes the insulator andsubstrate disproportionately more than the conductive R/W components dueto (1) the mechanical abrasion of the slurry against the bearingsurface, and (2) the chemical relationship between the slurry, thesubstrate, the insulator, and the R/W components. This leaves thecomponents of the R/W device 504 protruding with respect to the extendedplane of the bearing surface 508 of the substrate 502.

After task 706, the substrate 502 preferably defines a smooth, nearlyplanar bearing surface 508. Likewise, the insulator 600 may define asmooth, nearly planar surface 610, interrupted only by the protrudingR/W components 605. Due to the relative hardnesses of the substrate 502and the insulator 600, however, the surface 610 may be recessed somewhatwith respect to the surface 508. Unlike known sliders, the R/Wcomponents 605 preferably protrude from the surface 610, and even extendabove the extended plane of the bearing surface 508. With the describedmethod, the R/W components 605 may protrude between 10 nm and 150 nmabove the insulator 600, for example.

After task 706, task 707 is performed to create an "air bearing" on thesurface 508. Particularly, the surface 508 may be processed with aphotoresist or otherwise etched to create grooves that facilitatemovement of the slider 500 over the surface of a magnetic recordingmedia.

After task 706, task 708 may be performed (optionally) to deposit anearly uniform overlayer 606 to cover the substrate 502 and R/W device504, to protect the slider 500 from wear, contamination, and damage. Theoverlayer 606 may comprise a carbon-based material having a thickness ofabout 10 nm, for example. If desired, further float or contact polishingmay be preferred to thin or remove the overlayer 606 proximate the R/Wcomponents 605, so that the R/W components 605 may reside even closer tothe recording media during operation of the slider 500.

After task 708, task 710 is performed, where each row 200 is sliced intoindividual sliders. In an exemplary embodiment, each slider may be about2 mm long, 1.5 mm wide, with a thickness of about 800 μm. After task710, the routine 700 ends in task 712.

OTHER EMBODIMENTS

While there have been shown what are presently considered to bepreferred embodiments of the invention, it will be apparent to thoseskilled in the art that various changes and modifications can be madeherein without departing from the scope of the invention as defined bythe appended claims.

For example, different float or contact polishing parameters may beused, varying the time, speed rotation, pressure, particle size andtype, and the like. Additionally, the invention contemplates R/Welements with a different number, structure, or arrangement of R/Wcomponents, in substitution for, or in addition to, the shields, MRstripe, and pole tips.

What is claimed is:
 1. A method for manufacturing a slider for use as amagnetic read/write head, said method comprising the steps of:providinga substrate including a bearing surface and an adjoining deposit end;creating a read/write device atop the deposit end, by performing stepscomprising:layering an insulator over the deposit end, said insulatorcomprising a different material than the substrate; and providingread/write components by performing steps comprising:embedding amagnetic shield layer within the insulator; embedding a magnetoresistivestripe layer within the insulator; and embedding a magnetic pole tiplayer within the insulator; polishing the bearing surface with a lappingslurry to disproportionately erode the bearing surface and insulatorwith respect to the magnetic shield layer and the magnetoresistivestripe layer such that the magnetic shield layer and themagnetoresistive stripe layer both protrude beyond an extended plane ofthe substrate's bearing surface; and depositing a protective overlayerover the substrate, insulator, and read/write components said overlayerbeing reduced in thickness adjacent each protruding layer of theread/write device.
 2. The method of claim 1, wherein the lapping slurrycomprises an oxide material and a liquid.
 3. The method of claim 2,wherein the oxide material comprises silicon dioxide.
 4. The method ofclaim 2, wherein the oxide material comprises aluminum oxide.
 5. Themethod of claim 2, wherein the oxide material comprises cerium oxide. 6.The method of claim 2, wherein the oxide material comprises a ceramicmaterial.
 7. The method of claim 2, wherein the liquid comprises water.8. The method of claim 2, wherein the liquid comprises glycol.
 9. Themethod of claim 2, wherein the lapping slurry further includes asurfactant.
 10. The method of claim 1, wherein the substrate comprises aceramic material.
 11. The method of claim 1, wherein the substrateincludes TiC and Al₂ O₃.
 12. The method of claim 1, wherein thesubstrate comprises silicon.
 13. The method of claim 1, wherein thesubstrate comprises silicon carbide.
 14. The method of claim 1, whereinthe substrate comprises zirconium oxide.
 15. The method of claim 1,wherein the read/write components include a conductive material.
 16. Themethod of claim 1, wherein the read/write components includes a magneticmaterial.
 17. The method of claim 1, wherein the lapping slurrycomprises a material that is chemically erosive to the substrate andinsulator and the polishing step comprises the steps of float polishingthe bearing surface while chemically and mechanically eroding thesubstrate and insulator with the lapping slurry.
 18. The method of claim1, wherein the lapping slurry comprises a material that is chemicallyand mechanically erosive to the substrate and insulator and thepolishing step comprises the steps of contact polishing the bearingsurface while mechanically and chemically eroding the substrate andinsulator with the lapping slurry.
 19. The method of claim 1, whereinthe protective overlayer comprises carbon.
 20. The method of claim 1,the step of depositing a protective overlayer including a step ofpolishing the slider surface to reduce the protective overlayerproximate each protruding layer of the read/write device.
 21. A methodfor manufacturing a thin film head for exchanging signals with amagnetic recording medium, said method comprising the steps of:providinga substrate including a substantially planar bearing surface and anadjoining deposit end; creating a read/write device atop the depositend, by performing steps comprising:layering an insulator over thedeposit end, said insulator comprising a different material than thesubstrate; and providing read/write components by performing stepscomprising embedding a magnetoresistive stripe layer within theinsulator; polishing the bearing surface with a lapping slurry todisproportionately erode the bearing surface and insulator with respectto the magnetoresistive stripe layer such that the magnetoresistivestripe layer protrudes from an extended plane of the substrate's bearingsurface; and depositing a protective overlayer over the substrate,insulator, and read/write components, said overlayer being reduced inthickness adjacent the magnetoresistive stripe layer.
 22. The method ofclaim 21, wherein the lapping slurry comprises an oxide material and aliquid.
 23. The method of claim 22, wherein the oxide material comprisessilicon dioxide.
 24. The method of claim 22, wherein the oxide materialcomprises aluminum oxide.
 25. The method of claim 22, wherein the oxidematerial comprises cerium oxide.
 26. The method of claim 22, wherein theoxide material comprises a ceramic material.
 27. The method of claim 22,wherein the liquid comprises water.
 28. The method of claim 22, whereinthe liquid comprises glycol.
 29. The method of claim 22, wherein thelapping slurry further includes a surfactant.
 30. The method of claim21, wherein the substrate comprises a ceramic material.
 31. The methodof claim 21, wherein the substrate includes TiC and Al₂ O₃.
 32. Themethod of claim 21, wherein the substrate comprises silicon.
 33. Themethod of claim 21, wherein the substrate comprises silicon carbide. 34.The method of claim 21, wherein the substrate comprises zirconium oxide.35. The method of claim 21, wherein the read/write components include aconductive material.
 36. The method of claim 21, wherein the read/writecomponents include a magnetic material.
 37. The method of claim 21,wherein the lapping slurry comprises a material that is chemicallyerosive to the substrate and insulator and the polishing step comprisesthe steps of float polishing the bearing surface while chemically andmechanically eroding the substrate and insulator with the lappingslurry.
 38. The method of claim 21, wherein the lapping slurry comprisesa material that is chemically and mechanically erosive to the substrateand insulator and the polishing step comprises the steps of contactpolishing the bearing surface while mechanically and chemically erodingthe substrate and insulator with the lapping slurry.
 39. The method ofclaim 21, wherein the protective overlayer comprises carbon.
 40. Themethod of claim 21, the step of depositing a protective overlayerincluding the step of polishing the slider surface to reduce theprotective overlayer proximate the magnetoresistive stripe layer.